1. Field of the Invention
The present invention relates to a portable timer and in particular to a timer used to determined the duration of a first uteral contraction and the elapsed time between a first and a second uteral contraction experienced during childbirth.
2. Description of the Prior Art
As an expectant mother approaches delivering her child, she experiences numerous uteral contractions. The frequency of these contractions as well as their duration are of critical importance in determining how close the mother is to giving birth. Therefore, it becomes desirable to keep a log or history of both the duration of a single contraction as well as the distance between consecutive contractions. It is important that both of these values be recorded since the frequency of the contractions does not necessarily correlate to the length of the contractions. That is, simply because the contractions are more frequent does not necessarily mean that they last longer or vice versa.
The elapsed period between beginnings of subsequent contractions is commonly referred to as "how far apart" the contractions are, while the duration of a contraction is commonly referred to as the "length" of a contraction. Because physicians often instruct an expectant mother to proceed to a hospital after her contractions are a certain distance apart, one must, in addition to measuring the length of a single contraction, measure the distance between two contractions and compare it to the value prescribed by the physician. It is very cumbersome to monitor several pairs of consecutive contractions by using a conventional timing device since several time values must be recorded and operated on to determine the time between beginnings of two consecutive contractions. Moreover, without physically recording data relative to subsequent pairs of contractions, it is very difficult to monitor changes in contraction length and/or distances between consecutive pairs of contractions and then ultimately compare calculated distances apart to the target time value that was prescribed by the physician.
Conventional stop watches which measure only one event at a time are incapable of simultaneously calculating the distance between successive contractions. Even split time stop watches such as the one disclosed in U.S. Pat. No. 4,657,405 are not adapted to achieve the objects of the present invention. While the '405 patent describes an analog type stop watch which can measure the time of a first runner and the time of a second runner, for example, it is not adapted to display consecutive measured times of consecutive pairs of runners. The present invention, on the other hand, measures and displays a history of successive pairs of contractions. Finally, neither conventional nor split time stop watches are adapted to alert the user when the frequency of two events is greater than some preselected frequency.
3. Summary of the Present Invention
The present invention relates to a device which simultaneously measures and displays a plurality of pairs of measured times where the measured times include the elapsed period from the beginning of a first of two consecutive contractions to the beginning of the second contraction and the duration of said first contraction. Moreover, the present device comprises means for programming a user selected time interval representing some target time at which some further action must be taken. According to the present invention, said user selected target time is compared to the elapsed period between beginnings of consecutive contractions and warns the user if said elapsed time is less than said user selected target time.